US Patent 7509989 Window blind system

A unique window blind system has two triangular panels. Each panel has a plurality of foldable sections bundled together at one fixed end and the remainder portion are unfoldable to cover a diagonally opposite triangular half portion of the window opening. The panels are mounted in the window frame in an inverted manner relative to one another with the fixed end adjacent to diagonally opposite corners of the window frame. Pull cords are provided for folding the sections in a fanfold manner to obtain selectively an opening covering partially or completely the window opening. Additional pull cords are provided for unfolding the sections of the two panels to cover selectively the window opening partially or completely from the opened state.